Method and device for storing transport elements

ABSTRACT

The invention relates to a method and device for buffering with the use of a closed gripper. The invention comprises transport means ( 20 ) which are provided with grippers ( 22 ), can move along a conveying section ( 10 ), and are located in the area of a buffer section ( 14 ) of the conveying section ( 10 ). Transport means are stored in such a way that the distance between the transporting means ( 20 ), said means being successively arranged in the buffer section ( 14 ), is essentially determined by the degree of opening of the grippers ( 22 ) or by the dimensions of the transport means ( 20 ). Said means are also stored in such a way that opened grippers ( 22 ) are at least partially closed without exercising a holding function in or before the area of the buffer section ( 14 ). To this end, a closing device is placed in an entry area ( 16 ) of the buffer section ( 14 ) which, for example, can be provided in the form of a closing connecting member ( 18 ) and can be displaced along the conveying section ( 10 ).

The present invention relates to a method of, and an apparatus for,storing transporting elements according to the preambles of Claim 1 andClaim 9, respectively.

Conveying installations with conveying paths along which certainproducts can be conveyed with the aid of grippers are used in a widerange of industrial sectors, for example in the printing industry.Transporting means which are coupled in each case to the grippers haveto be stored on an intermediate basis in such conveying installations incertain applications. In particular, there is also the need for thesegripper-coupled transporting means to be stored on an intermediate basiswhen the grippers are not retaining any products.

Swiss Patent CH 382 768 discloses a buffer path in which, on account ofthe amount of storage space required by the gripper-coupled transportingmeans, only a relatively small number of transporting means can bestored in a buffer path of predetermined length.

Less storage space is required by grippers and transporting meansaccording to Swiss Patent CH 569 197, although this advantagedisadvantageously requires grippers and transporting means to be pivotedthrough 90° if a product is to be gripped by a gripper.

The object of the invention, then, is to make it possible for thetransporting means to be stored, without any significant disadvantagesbeing created in the process, such that they require the smallestpossible amount of storage space.

The method according to the invention provides that the storage spacefor transporting means is determined by the degree of opening of itsgripper or—in the case of grippers which are closed to a sufficientlypronounced extent—by the dimensions of the transporting means, and opengrippers are at least partially closed, without performing a retainingfunction, before the transporting means which are coupled to saidgrippers are fed to a buffer path. This means that, with the same numberof stored transporting means, the transporting means take up a shorterbuffer path than in cases based on known principles, in which opengrippers which take up a relatively large amount of space and are incontact with one another pass into a buffer path with the transportingmeans spaced apart from one another.

Since, according to the invention, a comparatively large number oftransporting means can be stored in a buffer path, it is advantageouslypossible for these to be moved relatively slowly within the bufferpath—if this is a constituent part of a conveying path—or to beintroduced into the buffer path, or retrieved therefrom, at low speed.

It is preferred if the transporting means are conveyed along the bufferpath, and the grippers are conveyed to such an extent that theirdimensions in the conveying direction are smaller than or equal to thedimensions of the transporting means in the conveying direction.

The grippers may be closed, for example, in that, in the inlet region ofthe buffer path, the transporting means are conveyed past a closingdevice, for example a closing guide, which then, e.g. in interactionwith a closing element of the gripper, close [sic] the latter.

The transporting means may be conveyed individually and independently ofone another, continuously or intermittently in the conveying path. Thiscan take place either actively, by each transporting element beingcoupled to a drive means via a retaining part, by means of which it isretained and guided in a guide element of the conveying path, or else inthat only individual transporting means are driven, these then pushingother, non-driven transporting means in front of them. Alternatively,however, it is also possible for the transporting means to be movedalong the conveying path, e.g. in a state in which they are decoupledfrom drive means, on account of an impulse imparted to each transportingmeans, or merely to individual transporting means, or on account oftheir own gravitational force.

In a buffer path according to the invention, it is basically possible tostore transporting means which are coupled to a driving means or areuncoupled from a driving means. It is thus possible to buffer-storetransporting means with or without drive means.

In a preferred embodiment of the invention, a closing device can bemoved along the conveying path. This displacement possibility makes itpossible for the length of the buffer path to be coordinated with thenumber of transporting elements which are to be stored. It is thuspossible, for example, to react in a flexible manner to irregularitiesoccurring in the operating speed of certain operating stations.

In a particularly preferred embodiment of the invention, thetransporting means, as they leave the buffer path, are guided past anopening device, which may be configured, for example in the form of anopening guide, with the result that only transporting means which areready for receiving purposes, i.e. transporting means with opengrippers, are available downstream of the buffer path, as seen in theconveying direction. The opening movement of the gripper legs preferablytakes place here in the conveying direction.

In that region of the conveying path which is located outside the bufferpath, the distance between the centers of two successive transportingmeans is preferably always somewhat smaller than or equal to the maximumdistance between two gripping legs of an open gripper. This ensures thatthe gripping legs of adjacent transporting means, in the open state, arealways in contact with one another and fix their alignment in relationto the conveying path.

In order to implement the method, use may be made of a conveyinginstallation according to Claim 9 which has a closing device justupstream of the buffer path or in the inlet region of the same. It islikewise possible for the closing device to be arranged such that thegrippers are closed immediately following a product-dischargingoperation, with the result that the gripper is ready for being stored onan intermediate basis immediately following said product-discharging.operation. The closing device may be designed in the form of a closingguide which may preferably be displaced along the conveying path, withthe result that the length of the buffer path can be adjusted in avariable manner in accordance with the respective requirements.

At the end of the buffer path, it is possible to provide an openingdevice, e.g. in the form of an opening guide, which ensures that onlytransporting means with open grippers leave the buffer path.

If the closing and opening device can be optionally activated anddeactivated, entire buffer paths can be connected up and disconnected asrequired.

A specific advantage is achieved if the three-dimensional extent of thetransporting means in the conveying direction, with grippers projectingperpendicularly from the conveying path, is smaller than orapproximately equal to the extent of the closed gripper in the conveyingdirection.

Further preferred types of method and advantageous configurations of theconveying installation in conjunction with the method according to theinvention form the subject matter of the subclaims.

The invention is explained by way of example hereinbelow with referenceto FIGS. 1 to 2, in which, purely schematically:

FIG. 1 shows a detail of a conveying path according to the inventionwith a section of a transporting path and an inlet region of a bufferpath with closing guide, said inlet region adjoining the transportingpath; and

FIG. 2 shows a detail of a conveying path according to the inventionwith an opening guide in the outlet region of a buffer path and with atransporting-path section which adjoins the outlet region.

FIG. 1 shows a detail of a conveying path 10 with a section of atransporting path 12 and a buffer path 14 which is arranged downstreamof said transporting path 12, as seen in the conveying direction A, andhas a closing guide 18 in its inlet region 16. Located in the conveyingpath 10 are transporting means 20 with grippers 22 which have aclosing/opening element 24. The grippers 22 are connected to a retainingpart 28 (merely indicated in the illustration), via a bearing element26. The retaining part 28 retains the transporting means 20 in aschematically illustrated guide element 30 of the conveying path 10. Forconveying purposes, the transporting means 20 may be coupled, via theirretaining parts 28, to a drive means 32 (likewise merely schematicallyillustrated) of the conveying path 10.

As seen in the conveying direction A in each case, the bearing elements26 of the transporting means 20 have an extent a which is only slightlygreater than the dimension of a width b of the closed grippers 22. Theretaining parts 28 are formed such that they do not prevent the mutualcontact of successive bearing elements 26 in the buffer path 14. As canbe seen from FIG. 1, the distance between the transporting means 20stored in the buffer path 14 is essentially determined by the dimensionsof the bearing elements 26, which are a constituent part of thetransporting means 20. If the bearing elements should be designed to beeven smaller than is illustrated in FIG. 1, said distance would bepredetermined by the dimensions of the closed grippers 22.

FIG. 1 illustrates how a transporting means 20 whose gripper 22 is openis conveyed, in the conveying direction A, from the transporting path 12to the inlet region 16 of the buffer path 14.

In the inlet region 16 of the buffer path 14, the transporting means 20is conveyed past a closing guide 18 which can be displaced, inparticular, in the conveying direction. The closing guide 18 acts on theclosing/opening element 24 provided on the gripper 22 and displaces thesame in the direction B, with the result that the gripper 22 is closed,without performing a retaining function. Only transporting means 20 withclosed grippers 22 are thus stored on the buffer path 14. This reducesthe length of the buffer path 14 which is required for storage purposes.

FIG. 2 illustrates an opening guide 34 in the outlet region 36 of abuffer path 14 and a section of the adjoining transporting path 12. Thetransporting means 20, which are approximately of axis-symmetricalconstruction, have their axes of symmetry 38 spaced apart from oneanother, in the region of the transporting path 12, more or less by anideal distance d, which is approximately equal to the distance d′between two gripping legs 40, 40′, which form the gripper 22, in theopen state. This ensures that the gripping legs 40, 40′ of two adjacenttransporting means 20 are in contact with one another, in particularunder mechanical stressing.

The situation illustrated in FIG. 2 shows how the transporting means 20which are stored in the buffer path 14 with closed grippers 22, which donot perform any retaining function, are conveyed past the opening guide34 in the outlet region 36 of the buffer path 14. In this case, theopening guide 34 acts on the closing/opening element 24 of the grippers22 and displaces the same in the direction C, with the result that thegrippers 22 are opened. At least the beginning of this movement of theclosing/opening element 24 is assisted in that the bearing elements 26are in contact with one another and supported against one another, as aresult of which good transmission of force to the closing/openingelement 24 becomes possible.

During the opening movement of the grippers 22, the transporting means20 are accelerated—if appropriate by suitable accelerating means—and/orcoupled to the drive means 32 by way of their retaining parts 28 suchthat they can be conveyed further on the transporting path 12, whichadjoins in the conveying direction A, at a distance apart from oneanother such that the open grippers 22 are in contact with one anotherin the manner described by way of their gripping legs 40, 40′. Thetransporting means 20 thus leave the buffer path 14 in a state in whichthey are ready for receiving purposes, i.e. with open grippers 22.

As can be seen from FIG. 2, the transporting means 20 are conveyed inthe transporting path 12, which follows the buffer path 14, in a statein which they are spaced apart from one another by the ideal distance d,with the result that the legs 40, 40′ of the grippers 22 are in contactwith one another and form a continuous zigzag line. It is thus notpossible for sheet-like products which are to be fed at a later point intime to pass between two adjacent grippers 22.

The transporting means 20 may be retrieved individually or in groupsfrom the buffer path 14 by suitable means, e.g. by mechanical releasemeans.

The buffer paths 14 illustrated in FIGS. 1 and 2 are illustrated in eachcase as an integral constituent part of the respective conveying path10. However, it is also conceivable for these buffer paths 14, ratherthan being configured as a fixed constituent part of the conveying path10, to be such that they can be removed from the conveying path 10 andreplaced by other buffer or conveying paths. This is advantageous, forexample, when it is desired for transporting elements 20 to be stored onan intermediate basis, and thus removed from the conveying path 10, fora relatively long period of time.

What is claimed is:
 1. Method for storing transporting means in a regionof a buffer path, the transporting means being the type that areprovided with grippers for retaining products and which are moved alonga conveying path in a conveying direction, comprising the steps of:moving the transporting means towards the buffer path with grippers thatare open and not performing a product retaining function; closing atleast partially the open grippers in the region of the buffer path orupstream thereof, storing the transporting means with the at leastpartially closed grippers in the region of the buffer path such that thedistance between transporting means following one after the other in thebuffer path is determined essentially by the degree that the grippersare open or the dimensions of the transporting means in the conveyingdirection.
 2. The method according to claim 1, characterized in that thegrippers are closed at least to such an extent that their dimensions inthe conveying direction are smaller than or equal to the averagedimensions of the transporting means in the conveying direction.
 3. Themethod according to claim 1 or claim 2, characterized in that thetransporting means are conveyed continuously or intermittently along thebuffer path.
 4. The method according to one of claim 1 or 2,characterized in that the transporting means are conveyed past a closingdevice which is provided in an inlet region of the buffer path.
 5. Themethod according to claim 4, characterized in that the closing device isdisplaceable along the conveying path.
 6. The method according to one ofclaim 1 or 2, characterized in that in the buffer path the transportingmeans follow one after the other so closely that adjacent transportingmeans are in contact with one another.
 7. The method according to one ofclaim 1 or 2, characterized in that the grippers of the transportingmeans are opened again in the outlet region of the buffer path ordownstream of the buffer path.
 8. The method according to claim 7,characterized in that, the grippers are conveyed past an opening device.9. The method according to claim 7, characterized in that the distancebetween the transporting means is increased as the transporting meansleave the buffer path.
 10. The method according to claim 9,characterized in that the distance between the transporting means isincreased in such a way that the gripping legs of adjacent, opengrippers are in contact with one another.
 11. The method according toone of claim 1 or 2, characterized in that the transporting means arestored in a buffer path which is located outside the conveying path oris an exchangeable constituent part of the conveying path.
 12. Themethod according to one of claim 1 or 2, characterized in that thetransporting means are retrieved individually or in groups from thebuffer path.
 13. Apparatus for storing in a region of a buffer pathtransporting means which are provided with grippers for retainingproducts, and which are moved along a conveying path in a conveyingdirection, comprising: a buffer path, means for moving the transportingmeans towards the buffer path with grippers which are open and do notperform a product retaining function; a closing device arranged upstreamof the buffer path or in the inlet region thereof for closing at leastpartially the open grippers in the region of the buffer path or upstreamthereof, means for storing the transporting means with the at leastpartially closed grippers in the region of the buffer path such that thedistance between transporting means following one after the other in thebuffer path is determined essentially by the degree of opening of thegrippers or the dimensions of the transporting means in the conveyingdirection.
 14. Apparatus according to claim 13, characterized in thatthe closing device is displaceable along the conveying path. 15.Apparatus according to claim 13, characterized in that an opening devicefor opening the grippers is provided downstream of the buffer path or inthe outlet region, thereof.
 16. Apparatus according to claim 15,characterized in that the opening device is displaceable along theconveying path.
 17. Apparatus according to claim 13, characterized inthat the closing device is activatable and disactivatable.
 18. Apparatusaccording to claim 13 characterized in that the dimensions of thepartially or fully closed grippers in the conveying direction aresmaller than or equal to the overall dimensions of the transportingmeans in the conveying direction.
 19. Apparatus according to claim 13,characterized in that the opening device is activatable anddisactivatable.